(1) Field of the Invention
The present invention relates to a black and glossy zirconia type decorative article and a process for the production thereof.
(2) Description of the Prior Art
A black decorative material formed by incorporating a pigment into an alumina ceramic material has been utilized, for example, as parts of a watch such as a watch case and a clockface. However, the alumina type decorative article is defective in that fine crystals are likely to fall down at the mirror polishing step conducted after the sintering step. Furthermore, since many voids are present in the crystals and the entire grain boundary, even if the mirror polishing is carried out, a mirror surface having a good smoothness and a deep gloss is not obtained. In this point, the alumina type decorative article is fatally defective.
Although this alumina type decorative article is excellent in the strength, when the decorative article is carelessly let to fall down and impinge against another article, the decorative article is readily cracked by a shock. In short, the alumina type decorative article is poor in the toughness.